In 1958 he left Canada to live and work in the United Kingdom. He was inspired by his compatriot Sydney Newman, who had been the Director of Drama at the CBC and had moved to the U.K. to take up a similar position at ABC Television, one of the local franchise holders of the ITV network who also produced much of the nationally networked programming for the channel.

At ABC, Newman as producer of the popular Armchair Theatre anthology drama programme, employed Kotcheff as a director of this series between 1958 and 1960.

Kotcheff was responsible for directing some of the best-remembered installments in the Armchair Theatre anthology series from 1958 to 1964.

During Underground, transmitted live on 30 November 1958, Kotcheff was required to cope with one of the actors suddenly dying while between two of his scenes.

In 1971, he directed the classic Australian film Wake in Fright (originally released in the USA in 1971 as "Outback", but re-released in 2012 with its original title[13]). It won much critical acclaim in Europe, and was Australia's entry at the Cannes Film Festival. (In 2009, Wake in Fright was re-released on DVD and Blu-ray disc in a fully restored version.)

In February 2016, Kotcheff applied for Bulgarian citizenship via the Bulgarian consulate in Los Angeles,[15][16] and was granted this during a visit to Bulgaria in March.[17] Given his Macedonian heritage, Kotcheff served on the Board of Directors of the Macedonian Arts Council. Per Kotcheff himself, there is not a difference between Macedonian and Bulgarian.[18]

^The Macedonian Conflict: Ethnic Nationalism in a Transnational World, pp. 85-89, by Loring M. Danforth: "The largest number of Slavic-speaking immigrants from Macedonia came to the United States during the first decades of the twentieth century, at which time they identified themselves either as Bulgarians or as Macedonian-Bulgarians".